Roof Space Ventilation Building Regulations

The open area of a vent is sometimes listed on the roof air vent as nfva net free vent area.

Roof space ventilation building regulations. The requirements will be met by the ventilation of those roofs where the moisture from the building can pass through the insulation. Building codes vary. As amended fitness of materials and workmanship c4. 2002 which deals comprehensively with the subject of condensation in dwellings.

In of vent opening per 150 sq. B resistance to ground moisture and weather and c5. Swish ventilators also meet the recommendations bs 5250. Isbn 978 1 85946 679 7 pdf 683kb this file may not be suitable for users of assistive technology.

Pitched roof spaces should have ventilation openings at eaves level to promote cross ventilation. Of vent for every 300 sq. A roof void above an insulated ceiling. Then aim for about 1 sq.

If not measure the size yourself. The building code lets you reduce that by half under some conditions but more roof ventilation is usually better. Ventilation 2010 edition incorporating 2010 and 2013 amendments ref. Where the void is open eaves to eaves air flow is effective along the longer sides of the building.

When ventilating a roof the air should be able to enter at one end and travel through to the other end where it can exit. In order to facilitate this exchange of warm and cool air the general rule of thumb suggests installing at least 1 sq. Roofs with a pitch of 15 or more. The building regulations northern ireland 2000 regulation b2.

Roof space ventilation introduction building regulation approved document c2 refers to bs 5250. In many pitched roofs a ventilation slot is built in along two opposite eaves so that air can flow across the roof space. In cold climates the primary purpose of attic or roof ventilation is to maintain a cold roof temperature to control ice dams created by melting snow and to vent moisture that moves from the conditioned space to the attic ventilation acts to bypass the vapour barrier created by most roof. The british standard code of practice for control of condensation in buildings as a means of compliance with a general requirement that adequate provision be made to prevent excessive condensation in a roof or.

The roof space isn t intended to be a storage area so if you. Both building regulations and nhbc require ventilation to be provided in roof spaces. Otherwise ventilation is required and this is known as a cold roof system.